Typically, pressure control valves are used if the travel speed of a hydraulic cylinder or the speed of a hydraulic motor is to be kept constant independently of the pressure difference prevailing on a flow valve, independently of the temperature or viscosity of a pressure medium used for this purpose and independently of the load to be moved. The pressure medium flow that has not been routed through the pressure control valve is drained via a pressure limiting valve for a pressure medium pump with relatively great losses in performance and pressure.
To minimize such performance losses, linking a pressure control valve that works as a pressure compensator to a load sensor on a consumer, for example, of a hydraulic cylinder, such that the LS (load sensing) pressure from the load sensor of the consumer prevails in a pressure chamber downstream of the pilot piston, is known. In particular, the pump pressure can be compared essentially to the spring pretensioning on the control piston plus the pressure on the consumer (LS). When the consumer is in the off-position, the pressure medium can be drained with less energy loss than in use with a pressure limiting valve. The performance loss of these known pilot-operated pressure control valves with a pressure compensator function, however, cannot be completely avoided.
DE 103 22 585 A1 describes, for example, a valve assembly for pressure control of a pressure medium from a pressure medium pump to a consumer, wherein a main control valve can be able to be hydraulically actuated by a pilot valve. In particular, the document describes a valve module system with at least one valve housing that, on its opposite ends both to the inside and to the outside on the periphery and in the housing interior, has standardized nominal sizes for mounting of other valve components. Such valve components can be a valve piston, an energy store, a pilot valve, and at least one fluid port for securing the valve assembly designed as a screw-in cartridge in the vicinity.
DE 10 2005 059 240 A1 shows and describes a hydrostatic drive system with a variable-stroke pressure medium pump that supplies a consumer with pressure medium via control valves. In idle operation of the hydrostatic drive system in which the control valves are not actuated, a pressure compensator used as a circulation device is set to a minimum control pressure difference. The pressure medium pump is set to a minimum delivery volume, with the pressure medium flow that comes from the pressure medium pump flowing via the pressure compensator to a pressure medium tank with low power loss.
The hydraulic drive system has a complex structure and does not have minimized pressure losses.
DE 689 08 317 T2 describes a pressure control valve whose main valve is pilot-operated by a pilot valve located in a common valve housing.